Maybe development has added more cars to the roadways. Maybe drivers are more pressed for time. Or maybe common sense and courtesy have no place in rush hour traffic.

Whatever the reason, South Shore roads are busier than ever and full of drivers who feel compelled to blow through red lights and speed through yellow, a Patriot Ledger survey of four of the region’s busiest intersections found.

Ledger news reporters stationed for an hour during morning and evening commutes at intersections in Quincy, Weymouth, Norwell and Plymouth witnessed 201 drivers blow through red lights. Many more hit the gas when lights turned yellow, including a police cruiser, an ambulance and a sheriff’s office vehicle, all without their lights flashing.

At the corner of Samoset Street (formerly Route 44) and Pilgrim Hill Road in Plymouth, motorists used all manner of techniques to beat the light. Three motorists were seen tailgating cars that turned left into oncoming traffic after the light turned red.

“On faster roads, drivers have more of a tendency to try to beat the lights,” Plymouth Police Capt. Michael Botieri said. “Really, it’s just that in a nutshell.”

Massachusetts motorists rack up about 80,000 “failure to stop” violations a year, Registry of Motor Vehicle records show. The violations include blowing stop signs as well as red lights. So far this year, 20,403 violations have been recorded.

Just because ticket writing hasn’t increased doesn’t mean running red lights hasn’t. Enforcement is down as police departments’ budgets are cut, and traffic officers are pulled from the beat to respond to emergency calls. Weymouth Mayor Sue Kay has had to cut millions out of the police department’s budget to make up for a health insurance deficit in town, and knows traffic problems are not being addressed.

“It’s very frustrating,” Kay said. “We can sit back and complain, but if I don’t have the money to heighten enforcement, we’re going to stay in the situation we’re in.”

Of all the violators the Ledger spotted in rush hour, not one was pursued by a police officer.

Area planners say drivers’ behavior goes hand in hand with the increase in commuters and traffic lights on the South Shore. Twenty years ago, some towns had no traffic signals. Now, even rural communities like Carver have at least one or two. The state issued permits for the installation of 26 new signals last year, and it’s almost unheard of for them to be removed.

“You probably get red-light running because people won’t sit through three traffic lights,” said Jack Gillon, Quincy’s traffic engineer. “They’re less likely to run one of them if they know they don’t have to sit through three of them.”

The Metropolitan Area Planning Council, a regional planning agency, counted 3.8 million average daily trips at 85 different checkpoints on South Shore roads from Quincy to Plymouth and greater Brockton in 2006. That’s up from about 3 million trips counted at 119 checkpoints in 2000.

Charlie Kilmer, transportation program manager for the Old Colony Planning Council, another regional planning agency, said motorists today are too rushed and on tighter and tighter schedules.

“Some people never grow up, they drive terribly their whole lives,” he said. “If you’re always skirting the red lights and you’ve never been caught, well, what would make you stop?”

There are consequences.

The number of car crashes in the four communities the Ledger surveyed were up 10.5 percent in 2005 compared to 2002, according to crash reports compiled by the Massachusetts Highway Department. A National Highway Traffic Safety Administration study showed that of all fatal crashes at traffic signals in 1999 and 2000, an estimated 20 percent involved failure to obey traffic signals.

The Insurance Institute for Highway Safety reports that nearly 900 people were killed and 144,000 injured nationwide in 2006 in crashes that involved running a red light.

Planners say a traditional way to reduce traffic congestion is expanding roads and intersections. The state’s widening of intersections at Route 18 in Weymouth, construction of a new parkway through the former South Weymouth Naval Air Station, and a new highway onramp at the end of Burgin Parkway in Quincy are a start. But any traffic improvement will be short-lived. New buildings planned in those areas will bring additional traffic.